ᐅ Painting basement floor with white efflorescence, built in 1960

Hello,

we have a terraced house built in 1960. In the basement (without a continuous concrete slab) there is a (cement?) screed with some old paint stains (see picture).

Basically, it is dry, with only very few white efflorescences in some spots. Only if you place a metal can on it, after a month there is a damp spot underneath.

The floor is partly rough (raw concrete/screed, etc.) and does not look nice. Now the question is, what should we do:

1) Liquid plastic, for example swingcolor 2in1 floor paint / liquid plastic 2in1 RAL 7031. But this is apparently not vapor-permeable. I am wondering if the floor would then be completely wet after a few months and the coating would no longer hold. It says the floor must be "protected against rising moisture from below."

2) A vapor-permeable epoxy resin, for example Remmers 2K epoxy primer with 2K floor coating. This might be good for the floor, but it could be a problem if I put cardboard/wood or similar on it for a long time, because moisture can still come from below. Even though it says it is "protected from moisture coming from the back during use."

3) A mineral, silicate-based solution was also recommended to me. I know silicate paint for walls since I have applied it there. Is there something similar for floors? Or what exactly is meant here? Well, vapor permeability makes sense for the floor, but the load is of course walking traffic. The floor is in a laundry room where maybe a little water runs on it once a week briefly.

There are neighbors with the same house who seem happy with epoxy.

What do you think?
Or completely different ideas?

Thanks in advance,
Jochen